There is a current of 25 A in a long straight wire. What is the flux density at a point 3 cm from the wire?
Correct answer: A. 1.67 x 10^-4 T
- A. 1.67 x 10^-4 T
- B. 3.67 x 10^-4 T
- C. 5.67 x 10^-4 T
- D. 7.67 x 10^-4 T
- E. 9.67 x 10^-4 T
Explanation
Given, a=3cm=9×10−2m, I=25AB=μoI/2πa=4π×10−7×25/2π×3×10−2=1.67 x 10-4 T
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About Electromagnetic Induction
Changing magnetic flux induces an emf according to Faraday's law, while Lenz's law gives the direction that opposes the change producing it. Transformers apply induction between coils to step alternating voltage up or down, with turns ratio, current transformation and energy losses determining practical operation.
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